This invention relates to a wireless communication apparatus such as a cordless telephone, capable of communication by wireless communication means.
Conventionally, carrier sensing in cordless telephones is performed independently by a main phone and a subphone. That is, the main phone monitors a carrier signal in radio waves emitted from the subphone, and if it becomes that the carrier signal cannot be detected for a predetermined period, the main phone stops transmission of radio waves. The subphone also detects a carrier signal in radio waves emitted from the main phone, and if it becomes that the carrier signal cannot be detected, the subphone displays an alarm message at predetermined intervals. When the carrier has not been detected for a predetermined period, the subphone stops transmission of radio waves.
Accordingly, in the above conventional cordless telephone, in a case where output power of radio waves emitted by the subphone becomes low due to, e.g., depletion of a built-in battery, the main phone cannot detect the carrier signal not necessary from the subphone, though the subphone may detect the carrier signal from the main phone. In this case, there is a problem that the main phone may stop transmission of radio waves while any alarm message indicating that no carrier has been detected at the subphone is displayed.